1. Field of the Invention
This invention relates in general to fault detectors and particularly to a novel electrically insulated indicator which is connected to a fault detector that monitors current in a power line.
2. Description of the Prior Art
Prior art fault indicators which are connected to overhead distribution lines have normally included an indicator that switches to a different color to indicate that the preset current limit has been exceeded. After the short has been repaired, and normal service has been restored, the indicator may be manually reset using a non-conductive pole or "hot stick". Some fault indicators include means for automatically resetting whenever normal load current has existed for a predetermined time period.
The advent of underground distribution systems requires that fault detectors be placed around the conductors at the bottom of access vaults. Also, the indicator device must be near the top of the vault so that it is not covered by water seepage. It is preferable that the indicator could be viewed without even opening the vault so as to speed up the searching process. The fault detector device along with the cable connected to the indicating device must be water-tight so as to provide for immersion for underground applications. Some electric utilities would not use immersible fault detectors because of the electrical hazard to repair crews. Distribution feeders operate at 12,000 v or even higher and represent a hazard if the insulation should fail and cause the high voltage to be connected to the indicator through the cable attached to the fault detector.
Fault indicators are devices used to indicate that the current and electrical power line has exceeded a preset limit after the time that the indicating mechanism was last reset.
Fault indicators may be installed on various branches of an electrical distribution system so as to provide information for repair crews who must find and repair the shorted element. Without fault indicators, the repair crew must operate on a trial and error method of disconnecting individual branch circuits and closing the network circuit breaker so as to determine if the isolated branch was the one in which a fault occurred.
Fault indicators connected to overload distribution lines include an indicator that switches to a different color to indicate that the preset current limit was exceeded. Once the short has been repaired and normal service has been restored, the indicator may be reset manually.